Patent GB-673934-A (GB)
Title: Improvements in the manufacture of felted layers of mineral wool fibres
IPC: D04H1/00
Filed: 1948-07-14
Abstract: 673,934. Fabrics composed of agglutinated fibres; compound fabrics; coated fabrics. JONES CO., Ltd., F., COLE, L. E., and BOWEN, D. M. July 14, 1949 [July 14, 1948], No. 18960/48. Class 140. In the manufacture of felted layers of mineral wool fibres by converting molten furnace slags, rocks, glass or like fusible substances into fibres by steam jets which blow the fibrous mass into a chamber having a floor constituted by a conveyer on which the fibres collect as a loose felt, a small proportion of a binder being thoroughly incorporated amongst the fibres as they are produced and before they are felted, a synthetic thermosetting resin, or a mixture of materials which will react to form the resin, is used as the binder, and is introduced into the fibres after the steam jets have exerted their fiberizing action, in such a manner as to ensure that there is no substantial precuring of the resin on the fibres, the loose felt after leaving the blowing chamber being subjected to a heat treatment to convert the resin to its insoluble final or cured form. The slag or other fusible mineral is melted in a cupola furnace 1, flows into a trough 2 and emerges as two thin streams from the ends thereof, adjacent each of which is a steam nozzle 3. An aqueous solution or dispersion of a thermo-setting resin, e.g. phenol-formaldehyde resin, contained in a tank 6, is discharged through a pipe 7, valve 8, visual indicator 9 and a T-piece, and is deposited on the fibres forwardly of their points of formation; or it may be atomized by compressed air and the resulting spray directed on to the fibres. In the form shown in Fig. 7, the resin solution is discharged through pipes 59 and T-piece 60 at points beside, and immediately in front of, the steam nozzles 62, and is directed by the steam jets into the mass of fibres, as a fine spray. The resin-coated fibres fall on a conveyer 4 in a chamber 5, and pass beneath a counterweighted roller 10 to a further conveyer 15, where they are subjected to pressure by rollers 17 and a wire mesh compression conveyer 26, both of which are hydraulically loaded, and the resin is cured by heating by infra-red lamps 25, or by hot air circulated in counterflow, gas powered infra-red radiators, steam coils, or highfrequency capacitance current heating. After cooling, the felt passes to a further conveyer 38 beneath circular knives 39 which slit it longitudinally, and is cut into lengths by a knife 41. A sheet of roofing felt, waterproofed or Kraft paper, metal foil, hessian, calico, muslin, wire netting, or expanded metal may be applied to the top surface of the felt from a roll 42, after the felt has been sprayed with adhesive from nozzles 43; the web is consolidated by rolls 45 and dried by heaters 46. To provide'the felt with " tacking edges " it is split longitudinally into a number of strips, which are separated by guide-members, and a roll of backing material, of width sufficient to overlap the edges of the strip, is used for each strip; or a single wide roll may be used, which is subsequently divided between the strips. Or, the felt may be entirely or partly enclosed in envelopes of the above materials by stitching or otherwise. Small quantities of water-repellants, such as oils or waxes, may be incorporated in the felts by atomization into the chamber 5. Sound absorbent tiles or pads may be produced by compressing the felt and providing one surface with a regular pattern of holes. A coating of a thermoplastic resin, e.g. a copolymer of vinyl chloride and acetate, or of a thermosetting resin, e.g. phenol-formaldehyde, may be provided ; the thermosetting resin may be applied over a pre-coating of a thermoplastic one.